Print shops are typically medium or large scale facilities capable of supplying printing services to meet a variety of customer demands. For example, print shops are often used to print documents used for mass-mailing (e.g., customer bills, advertisements, etc). Because print shops engage in printing on a scale that is hard to match, their customer base is usually varied. Print shop clients may therefore include both large institutional clients (e.g., credit card companies and banks), and small clients (e.g., small businesses and churches).
Print shops are generally arranged to print incoming jobs from clients in a way that is economical, yet fast. Thus, print shops often include a number of high-volume printers capable of printing incoming jobs quickly and at high quality. These printers may be managed by operators who can remove paper jams and reload the printers with media. Print shops also typically include post-processing devices that are used to process the printed documents of each job (e.g., stackers, staplers, cutters, binders, etc.). Because print shops serve a variety of clients, they are often tasked with printing jobs that have varying printing formats, delivery dates, and media requirements. Print shops therefore often use a centralized print server that coordinates activity between printers of the print shop and clients. The print server schedules incoming jobs and forwards them to the printers they are directed to.
In print shops, print servers may include dedicated print schedulers for directing incoming print jobs to different printers. A print scheduler receives print jobs directed to the print server, and assigns these print jobs to print queues for the printers. Once incoming print jobs have been scheduled, unanticipated events may occur that impact the printing time of a job in a queue. For example, a printer may encounter a paper jam that halts printing for several minutes, or a printer may be cleaned or aligned to restore optimal printing quality. In these situations, print jobs that have been assigned to the printer's queue take longer to print than originally anticipated by the print scheduler. This may be true even though other printers have become available to print the print job during the delay.